Low Delay Time All Optical NAND, XNOR and OR Logic Gates Based on 2D Photonic Crystal Structure

Background and Objectives: Recently, photonic crystals have been considered as the basic structures for the realization of various optical devices for high speed optical communication. Methods: In this research, two dimensional photonic crystals are used for designing all optical logic gates. A photonic crystal structure with a triangular lattice is proposed for making NAND, XNOR, and OR optical logic gates. Using the structure as the intended logic gate is possible without the need to change the structure through the use of the phase difference at the inputs. Line and point defects have been used to propagate light from inputs to output. The logical values "0" and "1", are defined based on the amount of transferred optical power to the output. Results: The simple structure and the use of line and point defects, instead of ring resonators, reduce the complexity of the design and its use in optical logic integrated circuits. Another advantage of proposed structure, in comparison to the previous structures is the reduction in delay time that increases its speed. The maximum delay time of the proposed optical NAND, XNOR, and OR gates is about 0.1ps. Conclusion: In this study, one structure is suggested for realizing NAND, XNOR, and OR logic gates. This structure has a small size and low delay time, and is suitable for use in optical integrated circuits.

Keywords:

Photonic crystals , optical gates , phase difference , Defects